壬基酚对羊角月牙藻的毒性效应研究

为研究壬基酚（NP）对淡水微藻的毒性效应特点，选取模式生物羊角月牙藻（Selenastrum capricornutum）为受试对象，设置5个暴露处理浓度：0.1，0.3，0.6，0.9，1.2mg/L.观察并测定羊角月牙藻的生长情况、叶绿素含量、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量等指标，并通过植物光合效率仪测定叶绿素荧光诱导动力学参数，分析NP对光系统Ⅱ（PSⅡ）的影响.结果表明，NP限制羊角月牙藻生长的96h EC50为0.979mg/L；NP处理浓度为0.3mg/L时，可以对羊角月牙藻生长产生抑制效应，与对照组相比，主要光合色素（叶绿素）含量下降，MDA含量显著增加，过氧化氢酶（CAT）和超氧化物歧化酶（SOD）活性显著上升，最大光能转化效率（Fv/Fm）显著下降，ABS/RC（单位反应中心吸收光能）显著上升，DI0/RC（单位反应中心耗散能量）、ET0/RC（单位反应中心捕获用于电子传递的能量）、TR0/RC（反应中心用于还原QA的能量）也随之升高；当处理浓度≥0.9mg/L后，CAT和SOD活性、TR0/RC显著下降，DI0/RC显著升高，表明PSⅡ受到损伤.由此可知，NP能够破坏膜系统完整性、诱发抗氧化系统响应并造成PSⅡ损伤，降低光能转化效率，对羊角月牙藻具有毒性效应，对水域生态系统具有潜在风险.

Toxic effects of nonylphenol on Selenastrum capricornutum

In order to investigate the toxic effects of nonyphenol (NP) on fresh microalgae, Selenastrum capricornutum was exposed to NP with concentrations of 0.1, 0.3, 0.6, 0.9, and 1.2mg/L. The growth, chlorophyll content, superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) were measured. Besides, chlorophyll fluorescence was obtained through a handy PEA, investigating the influence of NP on the PSⅡ reaction center. The results showed that the 96h EC50 of NP on S. capricornutum was 0.979mg/L. It was found that 0.3mg/L of NP could significantly inhibit the growth of S. capricornutum with decrease in contents of chlorophyll and maximal photochemistry (Fv/Fm), while increase in contents of MDA, activities of SOD and CAT, light absorbed by PSⅡ(ABS/RC), TR₀/RC and the dissipation of energy from reaction centers (DI₀/RC). More importantly, the cellular membrane system and PSⅡ reaction center of S.capricornutum were damaged obviously when the NP concentrations were higher than 0.9mg/L:the activities of SOD and CAT, and TR₀/RC were reduced, while DI0/RC was increased significantly. As a consequent, NP is toxic to S. capricornutum and it may be a potential risk to the aquatic ecosystem.